The present invention relates to an exposure control device and a distance measuring device.
Conventionally, exposure control devices are provided with a stroboscope or the like, for use in cameras or the like include one, in which a stroboscope is made constant in amount of luminescence, for example, at a time to change a diaphragm at the time of stroboscope radiation, depending upon a distance up to an object. Concretely, a diaphragm F serving as a standard at the time of stroboscope radiation is found from the following formula (1) on the basis of a distance L up to an object and a guide number GNo of a stroboscope, and the diaphragm F thus found is corrected on the basis of film sensitivity to provide a diaphragm F' at the time of stroboscope radiation, so-called, there is FM operation to provide a diaphragm F' at the time of stroboscope radiation. EQU F=GNo/L (1)
Also, some exposure control devices change an amount of luminescence of a stroboscope on the basis of a distance to the object to be photographed, and some ones automatically detect a distance up to an object.
With the above described exposure control devices, however, a reflection coefficient of an object is not taken account of, that is, it is assumed that a reflection coefficient of an object to be photographed is constant. Accordingly, in the case where a reflection coefficient of an object is high even when a distance up to an object is the same, an amount of luminescence passing through a shutter aperture increases in amount, and in the case where a reflection coefficient of an object is low, an amount of luminescence passing through a shutter aperture decreases in amount. That is, there has been a problem that an amount of luminescence passing through a shutter aperture varies due to a difference in reflection coefficients of objects to be photographed.
Also, the above described problem gives rise to a problem that, in the case where light passing through a shutter aperture subjects a sensitive member to exposure, a degree of exposure varies depending, upon a difference in reflection coefficients of objects to be photographed.
Further, there is a problem that a construction becomes large because of the need of separate constructions for detection of a distance up to an object and for detection of a reflection coefficient of the object when both of the distance and the reflection coefficient are to be detected.